<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="lib/jquery-3.3.1.js"></script>
</head>
<body>
    <div id="parent">
        <p>hello world</p>
    </div>
    <script>
    $(document).ready(function(){
        //coding 
        //jQuery选择器--支持所有的css选择器
        //$(selector).css() --改变元素的样式
        $("#parent p").css({color:"red",backgroundColor:"green"  });
    })
        </script>
</body>
</html>